The Seasonal Distribution and Migrations of Bearded Seals, Erignathus barbatus, in the Sea of Okhotsk According to Satellite Telemetry Data

AbstractThe life cycle and distribution of the bearded seal (Erignathus barbatus) are closely related to fluctuations of the ice edge during the year. The Sea of Okhotsk is a seasonally freezing water area, which is completely ice free in summer. This determines the annual cycle of the bearded seal and makes it unique compared to populations from other parts of the geographic range. Using satellite telemetry, the main seasonal habitats and migration patterns of the bearded seals have been studied in the Sea of Okhotsk. Seals use different areas during the ice-free and iced periods; they perform targeted long-distance migration in between these times. During the ice-free period, all bearded seals used the shallowest part of the Sakhalin Gulf. In the ice period, animals are distributed widely in the water area; they use offshore part of the Sakhalin Gulf, the northern and eastern coasts of Sakhalin Island. The timing of the formation of the ice cover has the largest affect on the dates and direction of seasonal migrations seals. The choice of seasonal habitats by the bearded seals is determined by the smallest available depths throughout the year and by the ice cover in the winter–spring period.